Metered mechanical tappet with slotted pushrod seat

ABSTRACT

A METERED MECHANICAL TAPPET UTILIZING A PUSHROD SEAT PERMANENTLY RETAINED BY A SEPARATE RETAINER OR BY A PRESSFIT WITHIN THE CAVITY OF THE TAPPER UPON AN ANNYLAR SHOULDER OF THE LATTER. OIL FLOW IS OBTAINED BY A SLOT IN THE SURFACE OF THE SEAT SUPPORTED BY SAID SHOULDER, THE SLOT AT LEAST EXTENDING RADIALLY FROM THE OIL RESERVOIR DIRECTLY BELOW THE SEAT TO THE OUTER WALL OF THE SEAT, FROM WHENCE IT PASSES TO THE INTERIOR OF THE SEAT AND TO THE PUSHROD BY MEANS OF AN ANNULAR PATH BETWEEN THE OUTER SEAT WALL AND THE CAVITY ALONG AT LEAST A PORTION OF THE AXIAL EXTENSION OF THE SEAT. THE ACTUAL METERING IS ACCOMPLISHED BY EITHER THE SLOT, IN WHICH THE CASE THE ANNULAR PATH HAS A SUBSTANTIAL RADIAL THICKNESS, OR BY THE ANNULAR PATH, IN WHICH CASE ITS THICKNESS IS CONSIDERABLY LESS THAN ANY OF THE DIMENSIONS OF THE SLOT.

Oct. 26, 1971 ERICKSON ETAL 3,614,942

R METERED MECHANICAL TAPPET WITH SLOTTED PUSHROD SEAT Filed April 20,1970 2 Sheets-Shoot 1 .27 ML? E50 26a. R 25% 6 42a,

30 fie I i1 I FIG. 2 66 INVENTORS RONALD R. ERICKSON RICHARD D. CORNELLBY ATTORNEYS Oct. 26, 197] ERICKSON ETAL 3,614,942

' METERED MECHANICAL TAPPET WITH SLOTTED PUSHROD SEAT Filed April 20,1970 2 Sheets-Shoot 2 TIG6 /46 INVENTORS RONALD R. ERICKSON RICHARD D.CORNELL ATTORNEYS United States Patent m Mich.

Filed Apr. 20, 1970, Ser. No. 29,915 Int. Cl. F011 1/14; F0lm 9/10 US.Cl. 123-9035 Claims ABSTRACT OF THE DISCLOSURE A metered mechanicaltappet utilizing a pushrod seat permanently retained by a separateretainer or by a pressfit within the cavity of the tappet upon anannular shoulder of the latter. Oil flow is obtained by a slot in thesurface of the seat supported by said shoulder, the slot at leastextending radially from the oil reservoir directly below the seat to theouter wall of the seat, from whence it passes to the interior of theseat and to the pushrod by means of an annular path between the outerseat wall and the cavity along at least a portion of the axial extensionof the seat. The actual metering is accomplished by either the slot, inwhich the case the annular path has a substantial radial thickness; orby the annular path, in which case its thickness is considerably lessthan any of the dimensions of the slot.

BACKGROUND OF THE INVENTION Although mechanical tappets do not requirehydraulic fluid for their operation in contrast with the hydraulictappets, nevertheless oil in many cases must be supplied to the rockerarms for lubrication thereof. A conventional way of accomplishing thisis by supplying the oil through the pushrod. Most prior constructions soutilizing the pushrod have resulted in improper control of the flow ofthe oil through the pushrod, and attempts to meter the flow have beenunable to overcome the problem of blockage due to foreign particles andat the same time not waste oil by having too much metering.

A very satisfactory metering device has been recently developed for usein mechanical tappets and is disclosed in application Ser. No. 853,741,filed Aug. 28, 1969, owned by the same assignee as the instantapplication. However, the construction disclosed in that applicationnecessitates the use of a fiat disc 40 upon which the push rod seatrests. To reduce cost, it would be advantageous to obtain a constructionwhich would not necessitate the use of the flat disc.

SUMMARY OF THE INVENTION The invention relates to a mechanical tappetutilizing continuous precision metering without the necessity for a flatdisc positioned immediately below the pushrod seat. Specifically, theinvention provides an improved mechanical tappet operatively connectedto a pushrod and comprising an oil reservoir, a pushrod seat positionedwithin a cavity of the tappet, the seat having a central openingcommunicating with the pushrod and means for metering oil from thereservoir through the seat and into the rod; the improvement comprisingthe metering means including a slot in one of the surfaces of the seatengaged by the tappet, the slot extending to the reservoir, and apassageway from the slot to the central opening.

Accordingly, it is an object of the invention to provide a mechanicaltappet utilizing precision metering without the necessity for a flatdisc positioned immediately adjacent to the metering surface of thepushrod seat.

It is a further object of the invention to provide a tappet of the abovecharacter wherein oil is supplied de- 3,614,942 Patented Oct. 26, 1971pendably and continuously to the pushrod regardless of the cycle of thecamshaft, the lack or the presence of lash, or the amount of the oilpressure.

A related object of the invention is to provide a tappet of the abovecharacter which is inexpensive to manufacture.

Other objects and advantages will become apparent upon reference to thefollowing drawings and detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, sideelevation partially in section of a tappet constructed in accordancewith the invention;

FIG. 2 is a plan view of the retainer utilized in FIG. 1;

FIG. 3 is a cross-sectional view of the push-rod seat and tappet bodytaken along the plane IIIIII of FIG. 1;

FIG. 4 is an elevational view, partially in section, illustrating thetappet body only;

FIG. 5 is a fragmentary side elevational view partially in sectionsimilar to FIG. 1 but illustrating an alternate embodiment;

FIG. 6 is a fragmentary elevational view, partially in section, of stillanother alternate embodiment of the invention;

FIG. 7 is a sectional view of the pushrod seat of the embodiment shownin FIG. 6;

FIG. 8 is a plan view of the tappet of FIG. 6 but without the pushrod;and

FIG. 9 is a cross-sectional view of a modified pushrod seat.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to animproved mechanical tappet 10 utilized in a conventional engine blockhaving a crankcase 11 and a passageway 12 connecting the tappet 10 to anoil gallery. The tappet includes the tappet body in which is seated apushrod seat 16 supporting a push-rod 14, the entire combination beingreciprocated in a conventional fashion by a cam 18 on camshaft 20. Thetappet body 24 is conventionally provided (FIG. 4) with an oil reservoir22 in the lower part and a groove 30 in the outer part thereof. Theupper portion is provided with an enlarged cavity 25 having thefollowing configuration. A shoulder 26 is formed by an annular undercut50. Spaced above the undercut 50 is still another undercut in the formof a groove 29. The shoulder 26 serves to accommodate and support theseat 16, while the functions of the undercut and the groove arehereinafter described.

In accordance with the invention, a metering means 36 is constructed inthe pushrod seat 16 so as to not need a flat disc as was utilized in theaforesaid application Ser. No. 853,741. The elimination of this elementis made possible by utilizing, in the embodiment illustrated in FIGS.1-4, a metering slot 40 (see FIG. 3) in the bottom surface of thepushrod seat 16, the slot 40 being positioned within the surface 42which rests upon the annular shoulder 26. The slot 40 extends radiallyfrom the outer wall 17 of the pushrod seat at least to a point at whichit is in communication with the oil reservoir 22.

To carry the metered oil from the slot 40 to a central opening 27 in theseat 16, a non-metering passageway comprising an annular path betweenthe outer wall 17 of the pushrod seat 16 and the wall of the cavity 25extending along at least a portion of the outer wall 17 is provided.Specifically, in the embodiment shown in FIG. 1, the annular pathcomprises the annular undercut 50 in the interior wall of the cavity 25,the undercut extending approximately half-way up the surface of the wall17. A cross hole 52 is provided within the pushrod seat 16, extendingradially from the center opening 27 to the wall 17 and thuscommunicating with the annular undercut 50. Thus, the flow of the oilfrom the reservoir 22 is through the metering slot 40, into the annularpath defined by the annular undercut 50, thence through the cross hole52 and into the central opening 27 where it passes through the opening28 in the pushrod.

The pushrod seat 16 having the preceding features can be manufactured byany conventional technique, such as by machining a suitable metal blank.The metering slot can be coined to insure proper size.

As in the case of the earlier aforesaid application, Ser. No. 853,741,to allow this metering device to be utilized, it is necessary to insurethat the pushrod seat 16 is biased at all times against the shoulder 26.To accomplish this, a resilient retainer 60 is pressed into the housing24 so as to prevent the surface 42 of the pushrod seat from separatingfrom the shoulder in the direction of reciprocation of the tappet. Thatis, tendency to separate will be caused by lash, and this tendency isprevented by the frictional retention of the retainer 60 within thecavity 25. The retainer 60 comprises a flexible metallic piece which isdish-shaped (FIG. 2) so as to provide an upstanding edge 62 formed by abend 64. A central hole 66 accommodates the pushrod 14. To insurepositive retention of the retainer 60 within the cavity 25, the groove29 may be provided within the cavity wall. (See FIG. 4.) However, it hasbeen found that the groove 29 is not essential to the proper retentionof the retainer 60.

It will be readily appreciated that the aforegoing construction allowsthe pushrod seat 16 to rotate within the cavity 25 with the surface 42pressed upon the shoulder 26 so as to lessen the tendency of the slot 40to become plugged. At the same time, this construction prevents anyaxial movement of the pushrod seat 16 so as to unseat and therebyenlarge the slot 40 allowing too much oil to meter into the cross hole52 and thence into the pushrod 14.

In operation, the oil flow to the rocker arm through the pushrod 14 isfrom the passageway 12, reservoir 22 defined by the tappet body 24,through metering means 36, and thence through the central opening 27 inthe pushrod seat to the hole 28 in the bottom of the pushrod 14. The oilin the reservoir 22 is replenished each time the groove 30' of thehousing 24 reciprocates past the opening to the passageway 12.

FIG. 5 illustrates an alternate embodiment of the invention wherein adifferent construction is utilized to retain the pushrod seat from axialmovement within the tappet. Similar parts which correspond to thoseutilized in the previous embodiment utilize the same numerals to whichthe distinguishing sufiix a has been added. Thus, as shown in FIG. 5, atappet a is operated by a cam 18:: within a crankcase 11a, the oilflowing from a passageway 12a through a reservoir 22a, slot 40a and upinto a pushrod 14a. The metering means 36a is identical in all respectswith that described in the previous embodiment except that the annularpath between the outer wall 17a of the pushrod seat and the inner wallof the cavity 25a is formed by reducing the diameter of the outer wall17a for almost the entire length of the pushrod seat. Thus, there is noannular undercut in the inner wall of the cavity 25a. The reduceddiameter of the outer wall 17a terminates at a point just below the topsurface 70 of the pushrod seat, thereby forming an annular lip 72, theouter diameter of which exceeds the diameter of the inner wall of thecavity 25a. This construction insures that the pushrod seat 16a will bepress-fit into the cavity 25a and retained in the position wherein itssurface 42a is constantly supported by the annular shoulder 26a of thecavity 25a.

It will be readily appreciated that because in the embodimentsillustrated in FIGS. 1 through 5, the metering is done by the slotrather than the annular path, that the radial thickness of the annularpath is substantial and the tolerances in forming the path are notimportant or significant.

FIGS. 6 through 8 illustrate still another embodiment wherein themetering is accomplished by the annular path between the walls of theushrod seat and the cavity of the tappet, rather than by the slot, sothat the slot merely conveys ample oil to the annular path under allconditions of operation of the device. Similar parts which correspond tothose utilized in the previous embodiments bear the same referencenumerals to which the distinguishing suffix b has been added. Thus, asshown in FIG. 6, a tappet 10b reciprocates within a crankcase 11b, theoil flowing from a passageway 12b, into a reservoir 22b and through aconveying means 3612 into a central opening 27b and thence up into apushrod 14b by means of the hole 28b therein. Unlike the previousembodiments, the metering in this embodiment is accomplished by theannular path between the wall 17b of the pushrod seat 16b in the wall ofthe cavity 251), a slot being provided in the bottom of the pushrod seat16 in the surface which rests upon the annular shoulder 26b solely forthe purpose of supplying continuously a flow of oil to the annular path.Thus, it will be readily appreciated that the radial thickness of theannular path is substantially less than any of the dimensions of theslot 80, the thickness being controlled by strict tolerance requirementson the dimensions of the walls of the pushrod seat and the cavity. Theparticular dimensions vary with the amount of metering desired, and arereadily determinable.

The embodiment shown in FIGS. 6 through 8 also illustrates that thecross hole 52b can extend the full diameter of the pushrod seat so as toprovide access to the central opening 27b by two different locations inthe annular path. Or, in the alternative, the cross hole 52b need extendonly as a radius of the pushrod seat. Further variations are to make thepush rod seat in two parts, the lower part being a disk as shown in FIG.9 with slots 80a, and 52d in opposite side thereof, and the upper partbeing the seat 17c. Reference numeral 520 designates the parting linebetween the two parts. This construction permits shallower slots andreduces flow characteristics.

Although the invention has been described in connection with severalpreferred embodiments, it will be recognized that other embodimentsequivalent in nature can be utilized. Thus, the invention is intended toinclude equivalent embodiments, unless the scope and wording of thefollowing claims expressly states otherwise.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.

1. In a tappet operatively connected to a pushrod and comprising atappet body having an oil reservoir, a pushrod seat positioned within acavity of said tappet body and supported by an annular shoulder of saidtappet body, means for restraining the pushrod seat against axialmovement away from said shoulder, said seat having an openingcommunicating with said pushrod, and means for metering oil from saidreservoir through said seat and into the rod; the improvement comprisingsaid metering means including a slot in one of the engaging surfaces ofsaid seat and said tappet body, said slot extending at least to saidreservoir, and a passageway from said slot to said central opening.

2. The improvement as defined in claim 1, wherein said passagewayincludes an annular path between at least a portion of the outer wall ofsaid seat and the concentric wall of said tappet body, and said slotextends from the outer diameter of said seat wall at least to a point incommunication with said reservoir.

3. The improvement as defined in claim 2, wherein said slot is apredetermined size to provide said metering, said annular path having asubstantially larger radial thickness than said size so as to have nometering function.

4. The improvement as defined in claim 3, wherein said path is definedby a substantial reduction in said outer diameter of said seat wall forat least a portion of the axial length of said seat.

5. The improvement as defined in claim 4, wherein said restraining meansincludes an annular lip on said seat and having an outer diameter whichexceeds the diameter of the wall of said cavity, whereby said seat isprevented from moving axially away from said shoulder.

6. The improvement as defined in claim 3, wherein said path is definedby an annular undercut in the wall of said cavity.

7. The improvement as defined in claim 6, wherein said restraining meansincludes an annular resilient dish-shaped retainer pressed between saidseat and said cavity wall.

8. The improvement as defined in claim 7, wherein said retainer issnapped into a groove provided within the wall of said cavity.

9. The improvement as defined in claim 2, wherein said passagewayincludes a radial cross-hole extending from said central opening to saidannular path.

10. The improvement as defined in claim 9, wherein said cross-holeextends the full diameter of said seat so as to provide access to saidopening at two diiferent locations in said annular path.

References Cited UNITED STATES PATENTS Black 12390.55

Line 123-9055 Dadd 123-90.48 Schumm 123-9035 Dadd 12390.35 Abell, Jr123-9035 Wortman et a1 123-9035 Humphreys 1846.9 X Dadd l23-90.55 X

AL LAWRENCE SMITH, Primary Examiner US. Cl. X.R.

